JPS5936456B2 - Failsoft direct relay device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fail-softened microwave direct repeater that prevents the communication system from operating even if the main repeater or power supply goes down.

In microwave relay systems that require high reliability, the operating rate of repeaters and auxiliary equipment is determined by the time it takes for a repair person to go to the relay station and make repairs in the event of a failure.

Therefore, it is desired to improve system reliability (operation rate) by implementing fail-software that can operate as a system even during this repair time. Conventionally, when the reliability of a repeater is low, since the reflector relay method used as a parasitic relay originally does not have an amplification function, system quality has been degraded as a section loss.

In order to remedy this problem, it was necessary to increase the transmission output of the terminal station or relay station that is the front station of the reflector relay, or to make the reflector larger. These methods have had problems with radio wave interference and line stability. In order to compensate for these shortcomings of parasitic relays, relay systems that directly amplify microwaves have recently been realized with low power consumption.

A solar cell power source is used as the power source for this repeater, but the low power consumption direct relay method that uses the solar cell power source has some reliability problems, so it is practically impossible to do so by duplicating the repeater, etc. It has a level of reliability comparable to that of reflector relays. Although the solar cells themselves are guaranteed to have high reliability, solar cell power sources use extremely random solar irradiation statistics and probabilistic methods to determine the solar cell capacity and battery capacity. The reliability of this repeater and the reliability of the solar battery power source are expressed probabilistically, but failure is an extremely serious problem in the case of direct relays that are constructed in locations where it is difficult to access stations, and this is a problem that can be solved using failsoft. Therefore, a method is needed to solve this problem. An object of the present invention is to provide a direct relay device that increases the reliability of a microwave relay system by making this system fail-soft within the fading margin allowed for the microwave communication system.

The present invention will be explained in detail below with reference to the drawings.

FIG. 1 is a block diagram of an embodiment of the invention.

This system is a bidirectional relay station, and the parabolic antennas 1 and 4 are used for both transmission and reception, but for the sake of explanation, antenna 1 and reception antenna 4 will be used for transmission.
First, radio waves received by the antenna 1 are guided to the input terminal 8 of the bypass circuit 2, and when the system is normal, the direct relay terminal 9 is directly connected to the input terminal 10 of the repeater main body 3 by a feeder or the like. The radio waves from the input terminal 10 are amplified by the main body 3, output from the output terminal 11, connected to the terminal 12 of the bypass circuit 2 by a feeder, etc., and sent out from the antenna 4 via the terminal 13. Further, 5 is a control circuit that controls the bypass circuit 2 based on the relay abnormality signal and power supply voltage abnormality from the main body 3, 6 is a solar cell module, and T is a storage battery E.
and a solar cell circuit board consisting of an overcharge prevention circuit 40, 8-
25 is a terminal. When the system is abnormal, the radio waves input from the terminal 8 are bypassed to the terminal 13 and emitted from the transmitting antenna 4.

Therefore, if the gain reduction of the relay system when bypassed from terminal 8 to terminal 13 is within the fading margin of the microwave communication system, it can be used as a microwave communication system and the system will not go down.
It will be made failsoft. Similarly, radio waves received by antenna 4 are transmitted to terminals 13 and 1 when the system is normal.
2, 11, 10, 9, and 8 in order, and is transmitted from antenna 1 through terminal 13,
8 and is sent out on the route of antenna 1. In other words, it has bidirectionality. The specific circuit of the bypass circuit 2 includes microwave switches 27, 29, 31 and a circulator 26.
, 30, and this figure shows the position of the switch during normal operation.

When the system is normal, the microwave switch 31 is off and the microwave switches 2T and 29 are on, and the radio waves input to the terminal 8 pass through the circulator 26, are reflected by the microwave switch 31, and are returned to the circulator 2.
6 and is sent directly to the repeater 3 from the terminal 9 via the microwave 27. Also, the output from the repeater main body 3 is terminal 1.
2. Through the micro switch 29, the circulator 30
and is sent to terminal 13. By configuring the circulator as described above, the leakage characteristics of the microwave switch 31 can be reduced. On the other hand, when the system is abnormal, the microwave switch 31 is closed and the microwave switch 2 is closed.
7 and 29 are disconnected, the radio wave input to terminal 8 passes through terminal 8, circulator 26, microwave switch 31, and circulator 30, is reflected at microwave switch 29, and then passes through circulator 30 and terminal 13. Bypassed.

A control circuit 5 for controlling the microwave switch of the bypass circuit 2 is connected to the control signal input terminals 14 and 15.

This circuit consists of a relay 32 that is activated by an abnormal signal from the repeater.
, but it may also be composed of an electronic circuit. The contact rl of this relay 32 is connected when the system is normal, and is opened when the system is abnormal, and the drive circuits of the microwave switches 2T, 29, and 31 of the bypass circuit 2 are connected in series to make the control system fail-safe. There is. That is, since current always flows through the drive circuit, even if a defect in the control system or power supply occurs and the bypass circuit is switched, the system remains on the fail-soft side. The Zener diode X1 is determined in combination with the resistor R1 so that the microwave switch is switched at the lowest voltage of the repeater used in this system. With this configuration, the solar cell system can be directly monitored with a simple method, and the control system can be made fail-safe. The structure of the direct repeater 3 consists of a circulator and an amplifier, and the radio wave input to the terminal 10 passes through the circulator 33, is amplified by the amplifier 34, passes through the circulator 35, and is output from the terminal 11.

On the other hand, the radio wave input to the terminal 11 is transmitted to the circulator 35.
, an amplifier 36, and a circulator 33 before being outputted from the terminal 10. The power source is supplied with solar power from terminal 25,
This voltage is supplied from the power receiving terminal 20 to the control circuit 5. 3
Reference numeral 7 denotes a power supply circuit that converts the solar battery power into a predetermined voltage, which is supplied to amplifiers 34 and 36 that amplify the microwaves and a monitor 38 that monitors abnormalities in the states of these amplifiers.

In addition, the monitor 38 supplies a ground potential to the terminal 21 during normal operation, and this ground potential drives the relay 32 in the control circuit 5 to supply current to the microwave switch. In addition, when an abnormality occurs, an open potential is supplied to the terminal 21, the relay 32 is turned off, and the relay contact (rl) is opened to prevent current from flowing through the microwave switch. The solar battery circuit board T includes a storage battery E, a backflow prevention diode X2, and an overcharge prevention circuit 40.
and is used.

A specific example in which the present invention is implemented in the 7 GHz band will be described. The repeater gain for making this configuration higher than the standard for the reflector repeater station can be calculated as follows. Here, a 20m copper oval feeder with one line for sending and receiving each feeder is installed.
If this is used, the loss will be approximately 2.5 dB1, and the circuit loss of the microwave switch, circulator, etc. will be approximately 2.5 dB.

In addition, the GANT has a 5mφ parabolic antenna gain (47.
5 dB), respectively, into equation (1), the repeater gain GREP becomes approximately 21 dB.

In other words, if the repeater gain is 21 dB or more, 8 ×
The quality is improved compared to 8m reflector relay.

However, since this system uses a reflector instead, the receiving frequency and the transmitting frequency are the same, so long echo distortion noise (generally interference noise) will be generated. This echo noise g/I
is determined by the coupling loss of the transmitting and receiving antennas and the repeater gain, and is expressed by the following equation. The upper limit of repeater gain is determined by this equation (2? echo noise).

If this echo noise is assumed to be 70 dB and the upper limit is determined, the large Mm will be approximately 40 dB, taking into account the degradation of antenna coupling loss due to reflections from buildings etc. near the relay station.

This value means that the system gain is 1 compared to the 8 × 8 reflector method.
Improved by 9dB. On the other hand, considering a fading margin of 50 d, if the repeater fails or the solar battery system goes down, if the repeater is bypassed, the fading margin is approximately 10 dB, but it cannot be used as a microwave communication system. be. This state can be set as a fail soft period, and repairs can be made during this period, improving the reliability of the system. In actual microwave communication systems, when such a relay system is introduced, it is often a short-distance system, and the relay gain is often 20 to 30 dB, so it is necessary to provide a fail-soft period with an even larger fading margin. I can do it. As described above, by rationally selecting the repeater gain, fading margin, and antenna coupling loss, it is possible to provide a fail-softening repeating system that is extremely effective in improving system reliability.

By introducing this system, the reliability of this microwave communication system is calculated using the following formula.

MTTR: 1 rush time + repair time (50Hrs) The reliability of this system is expressed as the probability of fading occurrence PR
= 1x10-3 (approximately 271c!n in plain propagation).

Furthermore, the effectiveness (EFs) of this system is expressed as a ratio of instantaneous interruption rates.

That is, as a result of the reliability comparison between the non-fail soft system and the fail soft system, it is found that the fail soft system improves the instantaneous rate by about 700 times.

FIG. 2 is a diagram showing the relationship between this result (EFs) and the fading occurrence probability for MF2=10 dB and 3 dB.

This system reduces the fading margin to 50 dB during normal operation in 7 GHz equipment with a repair time of 50 hours per trip.
1 abnormality is shown as 10 dB and 3 dB.

[Brief explanation of the drawing]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a diagram of the first embodiment.
FIG. 3 is a characteristic diagram showing the fail-softening effect of the system shown in the figure. In the figure, 1, 4... antenna, 2...
...Bypass circuit, 3...Repeater body, 5...
...Control circuit, 6...Solar battery power supply, T.
...Solar cell circuit board, 8 to 25...
Terminal, 26, 30, 33, 35... Circulator, 2T, 29, 31... Microwave switch, 32... Relay, 34, 36...
Amplifier, 37... Power supply circuit, 38...
Monitor, 40... Overcharge prevention circuit.

Claims (1)

[Claims] 1. A first transmitting/receiving antenna oriented in a predetermined direction, a second transmitting/receiving antenna oriented in a direction different from the aforementioned direction, a direct repeater that directly amplifies the microwaves received from these transmitting/receiving antennas, and a detection means for detecting a failure of the direct repeater and the power supply; and a switching means for switching the connection between the first and second transmitting/receiving antennas and the direct repeater; Directly connecting the first and second transmitting/receiving antennas when a failure is detected, and inserting the direct repeater between the first and second transmitting/receiving antennas when the detecting means does not detect a failure. A fail-soft type direct relay device characterized by switching connections so as to